Mechanical Interview Questions

Mechanical Interview Questions

I’m sharing this question list to fellow mechanical engineers that I made to prepare for an interview.

It contains two sections viz. technical questions followed by HR questions.

1. Technical questions:

Type of technical questions asked will be definition type and that too from basic. Your favorite subjects will be asked first and then they start questioning what they want you to answer.Some of the questions are…

1. Why we do not use same technology to start both SI/CI engine?

2. Which one is more efficient? A four stroke engine or a two stroke and why?

3. 4 Stroke engine is more efficient primarily Because of the presence of valves which precisely control the flow of charge into the chamber and exit the exhaust gases with proper timing which is hard to achieve by ports in a 2 stroke engine.

4. Why there is no differential in a train. What happens when a train takes a turn?

5. A cantilever beam is loaded a point on its ends what will be the effect in shear force?

6. Why vehicle does not move when its gear is applied though parked in slope area?

7. What is shear force in fluid particle?

8. How gear ratio helps in power variation?

9. What is the angle of twist in drill?

10. What is the difference between impact force and sudden force?

11. How to calculate the turbine efficiency?

12. Why centrifugal pump casing is called involutes casing?

13. What will happen if reciprocating compressor run in exactly opposite direction?

14. What is the effect of clearance volume in performance of air- compressor?

15. What is the advantages and disadvantages of critical speed of turbine?

16. What will happen if oil is mixed with boiler feed water?

17. What is difference between fan and blowers?

18. What are the protections required to protect turbine?

19. what is critical temperature?

20. Air is a bad conductor of heat. Why it becomes hot in summer?

21. How many stages in compressor in there in gas turbine?

22. Which is more efficient? A rear engine Volvo Bus or a Front engine Volvo Bus? (Engine Capacity is same for both) why?

23. What is difference between stress and pressure?

24. What is Boiler HP?

25. What is Auto Dosing?

26. What happens when too much oil is injected in the working cylinder?

27. How many manholes should be there on boiler? Why?

28. What is used to check the amount & quality of fuel in two stroke IC engine?

29. Work done in throttling process is given by which formula?

30. Function of the strainer in IC engine?

31. What is the difference between the air pre-heater & air blower?

32. Why the compression ratio of the diesel engine should be high?

33. A vertical plate and a horizontal plate are suspended in an open room. Both are heated to the same temperature. Which one will cool first? Why?

34. What is the color of flame if the boiler is running?

35. Which is the best lubricant-air, oil or water?

36. Tell the octane number in Indian petrol?

37. Difference between enthalpy & entropy?

38. What is the difference between safety valve and relief valve?

39. Explain cooling and its types?

40. What is the working principal of air compressor?

41. What is cryogenics and what are its fundamentals?

42. What is the difference between a shaper machine and a planner machine?

43. Why stress relieving of stainless steel is not proffered?

44. What are the advantages of PID controllers compared with those of a PLC?

45. Which two continents are mirror images of each other?

46. Where half nut is used?

47. What is the need for drafting?

48. Turbo charger driven by………….? and what its speed

49. Why…? Turbo charger used in DG….?

50. The stage below saturation is called?

51. Why is a condenser used in a Rankin cycle?

52. What is servo motor?

53. Can we use light duty vehicle axle into the heavy duty machinery axle? If no then why?

54. Stress strain diagram for fluid?

55. Where manning formula used?

56. What is level of documentations for a ISO 9001 certified company?

57. What is back plate in centrifugal pumps and its purpose?

58. Why tyres are manufactured in black colour?

59. Whether ductile material can fail in brittle manner? When?

60. On what property u can distinguish material as brittle or ductile?

61. Name fuels used in nuclear power plant?

62. On what thermodynamic cycle nuclear power plant works?

63. How can you increase the efficiency of power plant without changing in effort?

64. What is purpose of governor in Diesel engine?

65. Why petrol engines have more power than diesel engines of same capacity?

66. What is the difference between Torque and Power ( layman Idea)?

67. What will be the induced stress in the bar?

68. What is the Difference between Rated Speed and Economic Speed?

69. How to convert from HP to BHP or CC to Bhp please explain????????

70. How the material no. 2062 will mild steel of density 7.85? What are the other codes?

71. Why petrol engine gives more power than diesel engine even though diesel engine has high compression ratio?

72. What is mean by Resistance welding?

73. Compare Brayton and Otto cycle.

74. Why we have to know the specific frequency of any equipment? does anybody know about specific frequency ?

75. What is pulverization?

76. What is the function of an isolator?

77. Why the back wheel of tractor is bigger than front wheel?

78. Flow will increase or decrease or remain same?

79. Why Mechanical seal used in Pumps?

80. The ratio of Emissive to absorption power of heat by a body is equal to heat emitted by a perfect black body. Who said the statement

81. What is colour of flame if the of Halide Torch detects a refrigerant leakage?

82. How can we remove paint from (painted over)plastic or nylon objects with out damaging the object?

83. How to calculate or arrive the capacity of a mechanical press?

84. The property of a metal that is determined by the indentation on a metal surface

85. The amount of thickness of the metal sheet that can be welded by ultrasonic welding is?

86. The amount of carbon present in Cast Iron?

87. Numeric control is used for?

88. The amount of moisture that is to be present in wood to be called dry wood is?

89. The pattern material used in Investment casting Process is?

90. What is the use of offset follower in cam? Why and where we have to use this type of follower?

91. What is the use of offset follower in cam? Why and where we have to use this type of follower?

92. State the difference between Forging & Fabrication?

93. What is flange rating?

94. What amount of heat energy loss in ESP?

95. What happen when diesel is injected in petrol engine?

96. What do you mean by property of system?

97. Why joule-Brayton cycle is not suitable for a reciprocating engine.

98. How does “turbulence” differ from swirl?

99. Is octane number beyond 100 is possible?

100. Explain the effect of fuel structure on knocking.

101. Discuss the advantages and disadvantages of LPG as a fuel in S.I. Engine?

102. What is the impact of using throttling device instead of expander in vapour compression cycle?

103. What is moisture choking? Which refrigerants are more prone to it?